/*
  将下面异步代码使用 Promise 的方法改进
  尽量用看上去像同步代码的方式
  setTimeout(function () {
    var a = 'hello'
    setTimeout(function () {
      var b = 'lagou'
      setTimeout(function () {
        var c = 'I ♥ U'
        console.log(a + b +c)
      }, 10)
    }, 10)
  }, 10)
*/
function fn(msg) {
  var promise = new Promise((resolved, rejected) => {
    setTimeout(() => {
      resolved(msg)
    }, 10)
  });
  return promise
}

fn().then(function () {
  return fn("hello")
}).then(value => {
  return fn(value + "lagou")
}).then(value => {
  return fn(value + "I ❤ U")
}).then(value => {
  console.log(value)
})
